1. Field of the Invention
This invention is concerned with a novel method of making Zeolite S. Zeolite S may be utilized as an adsorbent, an ion exchanger and as a catalyst.
2. Description of the Prior Art
Zeolite S is known in the art, for example, U.S. Pat. No. 3,054,657 (Breck) is to a method of synthesizing zeolite S. The preparation of Species S zeolite is also described in the literature by Barrer et al.; J. Chem. Soc., 1959A, 195. Barrer et al.'s method leads to a product which also contains zeolite P and zeolite X as impurities. Barrer et al. used colloidal silica as the source of silicon and aluminum hydroxide as the source of aluminum. Colella and Aiello, Rend. Accad. Sci. Fis. Mat., Naples 1971, Vol. 38, Page 243, used rhyolite glass as the silicon and aluminum source; the reaction took place in a non-reactive teflon container. Rhyolite is based upon and/or formed from volcanic materials. The Breck patent's source of silica and alumina was derived from sodium silicate or colloidal silica and sodium aluminate.
Zeolites are usually made by mixing silicate and aluminate solutions and heating the resulting gel-solution mixture until a complete crystallization is obtained. Zeolites have a tetrahedral framework of oxygen ions about silicon and aluminum ions with each zeolite having its particular range of silicon to aluminum ions. The silicon/aluminum ratio is a function of the composition of the reaction mixture. Accordingly variables can be introduced into or via the mixture, some of which include:
(1) SiO.sub.2 /Al.sub.2 O.sub.3 ratio, (2) cations or ratio of cationic species, (3) concentration of the alkali, (4) pH, (5) seeding, (6) temperature and (7) time. Variation in the silica to alumina ratio of the starting mixture influences the type of crystal structure formed, e.g., zeolites A, B, or X. Another variable may be introduced by complexing part of the aluminum with ions other than hydroxyl.